Fly cutter



L. A. sMrrH Aug. 27, 1946.

FLY GUTTER Filed Aug. 11., 1945 my W w. @a

provide a cutter of the Patented Aug. 27, 1946 FLY CUTTER Lawson A. Smith, Los Angeles, Calif., as signor to Robert H. Clark, Los Angeles,

Calif.

. Application August 11, 1943, Serial No. 498,214

, 1' This invention relates ticular reference to that type of cutter generally known as a fly cutter. A generalobject of the invention is to provide a, simpleysturdy and highly efficient toolof this character.

Adjustable cutters of the type known `as fly cutters are commonly used for various cutting operations, particularly for cutting round holes in sheet materials of different kinds, and they 'operate to cut an annularjgroove or channel and thereby remove a round disc or slug. Ordinary devices of this character are not altogether satisfactory, due primarily to the fact that they are not sufliciently rm or rigid and are such that there is a marked tendency for them` to chatter while in use, and frequently they tend to dig into the work, resulting in the breakage of cutters. It is an object of the present invention to provide a construction for a cutter of the character referred to that is extremely simple and compact, making it inexpensive of manufacture and highly practical to use.

Another object of the invention is to provide a simple, sturdy construction that operates to rmly support the cutting parts and thus eliminates uneven operation or chatter such as commonly occurs in devices of this character. y

Another object of my present invention is to which the cutter-carrying arms are` supported close to the lower end of the body so`that the space between the body and the work is minimized.

A further object of this invention is to provide a cutter of the character mentioned in which the cutting tools are supported so that their cutting parts or edges are related Vto the points at which the cutters are supported by the arms in a manner so that the cutters tend to lift away from the work or be relieved rather than to dig into the work in a manner to cause injury to the parts.

Another object of my invention is to provide an improved pilot construction for tools operating to make an annular cut. I provide a pilot that effectively holds the work and also guides the cutter.

The various objects and features of my invention will be fully understoodfrom the following detailed description of a typical preferred fOrm and application of my invention, throughout which description reference is made to the accompanying drawing, in which:

Fig. 1 is a side elevation of a typical preferred 55' character referred to into a cutter Vand has parend of the body. The arms A'7 Claims. (Cl. 77-69) form of my present invention. Fig. 2 is another yside View of the device taken in thel direction of lines 2-2 on Fig. show in section,

and Fig. 3 is an end elevation Vof the cutter, being a view taken as indicated by for securing the arms in the desired position relative to the body, cutters I4 carried by the outer end portions of the arms to depend therefrom, retaining means I5 for the cutters operable to rmly set 0r grip them in the desired adjusted positions, and a pilot the lower end of the body IIJ. y

The body of the tool provided by my invention is preferably in the form of a unitary block of steel, or the like, having considerable mass and proportioned so that it .is inherently rigid and solid. In the preferred form of the invention the body is polygonal in cross section, for instance it may be hexagonal as shown in the drawing. The body is made` sufficiently long to Vaccommodate the various parts hereinafter described and its lower end 2U is preferably finished so that it is flat and lies in a plane normal to the longitudinal axis of the body and of the tool.

The shank H projects upwardly from the body concentrically therewith, and formed integral with the body as shown in the drawing. The shank is provided as a means for applying the tool to a machine or operating device and to this end may be designed and proportioned to t such driving means. For ordinary purposes kit is desirable to provide a tapered shank as is shown in the drawing. 1

The arms l2 are slidably carried in channels 2 l` formed parallel to each other in diametrically opposite sides of the body I0 adjacent the lower `are preferably in the form of elongate member or bars preferably square in cross section, and are adapted to be arranged in various adjusted positions in the channels in order to vary the positions of the cutters which are carried by their outer ends.

The channels 2l which slidably carry the arms I2 are located opposite each other in diametrical- 1y opposite sides of the body and are located close to the lower end 20 of the body so that there` is but ashort distance between the lower sides of 1 with a portion broken' away to y I6 depending centrally from is preferably the arms in the body may be 3 preferred construction v `.threaded into the sides of the body which are 1 channeled and I provide disc shaped clamping i outer faces of the arms l channels 2|. i clamping members 3| 'or the edge se.

g cutting parts of ter are located below the Y their cutting parts are taining the cutters theV arms and the bottom ofy the body. VThrough ,this construction the arms are supported by the Vzbody in a position as close as practical to the bottom end of the body.v

The means I3 provided for retaining or setting that will adequately serve this purpose. In the I provide cap screws 30 members 3i on the cap screws to bear on the against the arms to lfirmly secure them against longitudinal movement in the channels. Y The cutters practice the lower end portions of the cutters I are finished or dressed so that each cutter has ya lower cutting edge 36. The lower cutting edges 35 of thecutters are pitched from the horizontal so that each cutter has a lower cutting point 31 and the two cutters are dressed so cutter A is at the inner end of the edge while the point 31 of the cutter The sideY tending up from the lpoint is preferably dressed to recede and have clearance vas the A cutter advances.

In accordance i4 are disposed so that they do not track 1n .eX- actly the same paths but rather the cutter A operates to cut the inner 'portion or wall of the cut vwhile the cutter B operates to cut the outer portion or wallof the cut. This 'may be accomplished by dressing the cutters so thatv their cutting edges and points are suitably disposed. However, in practice it is desirable to formthe channels 35 which carry the cutters softhat the the cutters are properly located.

in the case illustrated the channel which carries the cutter A supports it so4 that it is in a truly vertical position when viewedas shown in Fig. l, while the channel 35 which Vsupports the cutter B is pitched downwardly andjoutwardly enough to locate the point, 31 of the cutter B a suitable distance outward of the path of the cutter A.

In accordance with rny invention the channels 35 Vin the arms i2 carrying theV cutters vlll are pitched downwardly and rearwardly with reference to the direction of rotation of the cutter so that the cutting points and edges of each cutyarm and rearward of the point at which the cutter is supportedby the arm with reference to the direction in which the cutter'is rotated. Y. Thaty is to say, the cutters Ilil are pitchedY to depend ldownwardly and, rearwardly relative to the directio'nof-cut so that behind the point ati which the cutters are supported by the arms. Through this construction, should thecutters feed too fast into the material, they willV tend to be forced back and to lift from Y to bite into it. It is to be understood, of course that theforward facesrt of the cutters immediately above the edges 35 are dressed yorffaced so that the cutters give the chips the desired clearance.

The means l5 provided byl my invention for re- !4 in the desired adjustedlposition may varyas circumstances require, In the case illustrated I have shownathe'outer `end porany suitable means that the point 31 of thev Bf is at the outer end` 31a of the cutterex-` with my invention the cuttersv the material rather than to clamp thernrinto the i By tightening the cap screws the are effectively forced I4 are elongate bodies of cutting 1 1 material, such as tool steel, carried in channels 1 35 formed substantially vertically Yin the outer end portions of the armsi 2. In

35 so that the part d2 'defining one wall. of the channel, can be sprung to grip the cutter. A

" clamp screw K13-is threaded to the part d of the end portion ofthe arm andengages the part B2 in a manner to'clampit tightly against the cutter. My present invention provides an improved pilot lconstruction applicable, generally,to Vrotary cutters or to cutters operating to make anannular cut in the work. My invention provides, pri- `marily, a pilot rod 50 slidably carried by the body concentric with the axis of rotation and means Vinrconnection with the pilot rod 6% Vto normally yieldingly ,urge it downward from the lower end of .the bodyv to engage Athe work as the cutter operates. The invention further provides means for retaining the-'pilot rod in the body and a pressure plate 6i in connection with the pilot rod to bear on the work.

In the preferred construction'the body is providedwith arcentral socket 62 extending into it from its lower end. The socket' may be formed by providing .a central boreintheA body from its lower end. The pilot rod may be a plain,`straight, 4round .bar which'slidablyV fits l.the socketuZ and proportioned so that its/lower end portion' projects aV suitableV distance fromthe lower end of thebody It, while `its'upper `end terminates a suitable distance short of the upper end ofthe socke`tl2'."V 'mi i VA compression spring 63 socket 62 above the rod '60 orY between the top of the rod and the upper'end of the socket, so that it normally yielding'ly urges'the' rod downwardly.

Various means may the rodin .the socket. Inthe construction shown I have provided a reduced portionli at a suitable point along the length of the rod, that is," at Aa poinit'withi'n the body lll, and'have provided a stop Yscrew S6 in 4the 'bodyto project finto :the

socket to the reduced portion of the'rodt'oiact .Y

the rod is provided with a' point or` center 66 lwhich may be used to engage the work, stanceto ,engage center .holel erneuter punch mark provided inthe work. I-nacocrdance my inventionIprovi'de .a Vpressure `plate 61 that can be used inr connection with This vplate maybeinthe'fo'rm of a disc having" a central'tapered socket 61 designed to 'be'l engaged bythe point 63 of the pilot rod. ,'The-Ibllom face SS of the plate Vlili is flat and designed-to bear on the work, giving a largebearing surface to have a clamping effect.

being used to cut gaskets, orvthelikegforfinstance, whenit is being used on materialsthat are soft or flexible, it is desirable to usethe pressure plate 6l as'it 4will have a desirable holdingor clamping effect A(in the partr which'isicut outY by the action of thetool. VWhen the tool is 'being used on harder materials or metals "it'jniay be sufiicient to merely allow the center Gs'ofthe Apilotrod .to engage ra small pilot hole Yor center Vpunch markprovided in the work. The spring Vt?, maybe Ymade suclir as `to` exert 'af suitable amount of pressure on the pilot rod' and .this may be varied according to the :work being'do'ne. The spring-may be such as to merely provide a holdingpressure to hold the work in placeborit may be made fairly strong, so thatA it acts' to eject the .part cutout by the action of Ythe,toolgvjl,v

In using the device .thearms `L2 are adjusted fito .project the; desired :distances from theggbody 'is arranged in vthe Vbe provided for retaining- 'with 'the' pilot rod.

When the tool is v and are set in such adjusted positions by the means I3. I4 are arranged in the overlap while the path of the cutter A extends inwardly from that of the cutter B so that the cutter A makes the inner portion of the out while the cutter B makes the outer portion of the cut. During the cutting operation the pilot rod, or the pilot rod with the pressure plate under it, bears on the work, the rod and holding the work, particularly the slug or disc portion that is cut out by the tool. v

Having described only a typical preferred kforni and application of my invention,v I do not wish to be limited or restricted to the speciic details herein set forth, but

scope of the following claims:

Having described my invention, I claim:

1. A cutter of the character `described including a central elongate body having outwardly opening cutter carrying channels formed in it at diametrically opposite sides and at right angles to the longitudinal axis of the body, arms slidably carried in the channels to project laterally from the body, means for individually clamping the arms laterally of the longitudinal axis of the body to hold them against movement in the channels including clamp members engaging the arms to bear on them laterally of the axis of the body and a screw member pend therefrom.

2. A cutter of the character described including a central elongate body having open cutter carrying channels formed in it from diametrically opposite sides extending at right angles to the longitudinal axis of the body, arms slidably carried in the channels to project laterally from the body, means for individually clamping the arms against movement in the channels, and cutters carri d by the arms to depend downwardly therefrom and rearwardly of the direction of cut so these cutting parts are behind the points at which the cutters are supported by the arms.

3. A cutter of the character described including a central elongate body having transverse cutter carrying channels formed parallel to each other in opposite sides of the body and open at their outer por-tions, arms slidably carried in the channels to project from the body, means for individually clamping the arms laterally of the longitudinal axis of the body and against the bottoms of the channels so theyare held against movement in the channels, and cutters carried by the projecting portions of the arms to depend therefrom.

wish to reserve to myself v any variations or modications that may appear operating each clamp j. member, and cutters |carried by the arms to def ing channels in it at diametrically opposite sides 4. A cutter of the character described including a central elongate body notched at opposite sides to have transversely disposed cutter carryparallel to each other and adjacent the lower end of the body, arms slidably carried in the channels to project laterally from the body, means applied to the exterior of the body at the sides of the body for clamping the arms in the channels against movement in the channels, and cutters carried by the projecting end portions ofthe arms to depend therefrom.

5. A cutter of the character described including a central elongate body having laterally disposed cutter carrying channels formedsin it at diametrically opposite sides, arms slidably carried in the channels to be parallel with each other and to clamping the arms against movement in the channels, and cutters carried by the projecting portions ofthe arms to depend downwardly therefrom and. rearwardly of the direction of cut so the cutting edges of the cutters are behind the points where the cutters are supported by the cutting edge being pitched and terminating in a cutting cutters overlapping and the point of one cutter being at the inner end ofthe edge and the point of the other cutter edge.

6. `A cutter ofthe character described includving a central elongate .body having outwardly opening cutter carrying channels formed in it at diametrically opposite sides and at right, angles to the longitudinal axis of the body, arms slidably carried in the channels to project laterally from the body, means for individually clamping the arms against movement in the channels,V there being a central opening extending into` the body between the channels, a pilot member carried by said opening to project from the lower end of the body, a spring in the opening normally yieldingly urging the pilot downward, and cutters carried by the arms to depend therefrom.

7. A cutter of the character described including a central elongate body having laterally opening transversely dispo LAWSON A. SMITH.

project from the body, means forV point, the paths of cut of the being at the outer end of the 

